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P0442

Evaporative Emission System Leak Detected (Small Leak)

P0442 means the computer found that the fuel-vapor system cannot hold vacuum or pressure the way it should during its self-test, but the leak is smaller than a gross leak like P0455. A loose gas cap, weak cap seal, cracked hose, leaking purge or vent valve, damaged canister, or tank-seal problem can all trigger it. The car often still drives normally, but the leak needs to be found and repaired.

SEV
2/5
DRIVE
YES
DIY
$0-$150
SHOP
$90-$450

Quick answer

AI-CITATION READY

What it means

P0442 means the powertrain control module detected a small leak in the evaporative emissions system. The EVAP system stores fuel vapors in a charcoal canister and then feeds them into the engine through purge and vent controls. A worn gas-cap seal, small crack in a vapor hose, seep at the filler neck, purge or vent valve that does not seal fully, canister leak, tank-pressure sensor issue, or minor sealing fault around the fuel tank can keep the system from passing its leak check.

Can you drive with it?

Yes. You can usually keep driving with P0442 because it does not normally create an immediate safety or drivability problem. Repair it soon if you smell fuel vapor, keep failing emissions checks, or see the code return quickly after clearing it.

Most common causes

  • Loose, incorrect, or weak fuel cap seal
  • Small EVAP hose crack, split line, or loose fitting
  • Purge valve or vent valve not sealing completely during the monitor

Typical repair cost

DIY usually runs $0-$150. Typical shop repair lands around $90-$450, depending on the root cause.

01 / Definition

P0442 means the powertrain control module detected a small leak in the evaporative emissions system. The EVAP system stores fuel vapors in a charcoal canister and then feeds them into the engine through purge and vent controls. A worn gas-cap seal, small crack in a vapor hose, seep at the filler neck, purge or vent valve that does not seal fully, canister leak, tank-pressure sensor issue, or minor sealing fault around the fuel tank can keep the system from passing its leak check.

02 / Drive status

Yes. You can usually keep driving with P0442 because it does not normally create an immediate safety or drivability problem. Repair it soon if you smell fuel vapor, keep failing emissions checks, or see the code return quickly after clearing it.

03 / Symptoms

  • Check engine light
  • Failed emissions inspection
  • Fuel smell near the vehicle in some cases
  • Code may return after being cleared
  • Usually no obvious drivability change

04 / Causes

1Loose, incorrect, or weak fuel cap sealhigh
2Small EVAP hose crack, split line, or loose fittinghigh
3Purge valve or vent valve not sealing completely during the monitormedium
4Minor leak at the charcoal canister, filler neck, or fuel tank sealmedium
5Fuel tank pressure sensor or leak-detection logic reading inaccuratelylow

05 / Diagnostic sequence

  1. 01Confirm the code, record any related EVAP codes such as P0440, P0441, P0455, P0456, or P0457, and do not clear anything until the basic inspection is done.
  2. 02Inspect the gas cap for looseness, cross-threading, the wrong cap design, or a hardened or torn seal, then tighten or replace it if needed.
  3. 03Check EVAP hoses, hard lines, the filler neck, and the canister area for small splits, rubbed spots, or disconnected vapor lines.
  4. 04Test or command the purge and vent valves to make sure they seal when closed and flow when commanded open.
  5. 05Use a smoke test if the leak is not obvious, because small leaks are often hard to find by eye alone.
  6. 06Inspect the charcoal canister, tank-seal area, and fuel tank pressure sensor wiring if the cap and hoses look okay.
  7. 07Clear the code after repairs and complete the EVAP monitor drive cycle to confirm the leak test passes.

06 / Repairs

1Tighten or replace the gas cap if the seal or cap fit is weak$0-$35
2Repair or replace cracked EVAP hoses, vapor lines, or loose fittings$20-$180
3Replace a purge valve or vent valve that fails sealing or flow checks$50-$220
4Repair a leaking canister, filler neck, tank seal, or pressure-sensor fault if testing points there$80-$450

MFG / Manufacturer notes

These supplements add make-specific diagnostic framing. Pages without full matrix backing or lane approval stay guarded and canonicalize back here until they are explicitly approved for indexing.

  • Dodge P0442

    Expansion-candidate noindex child page

    Open

07 / Related codes

  • P0440
  • P0441
  • P0455
  • P0456
  • P0457

08 / FAQ

What does P0442 mean?

It means the EVAP system detected a small leak while checking whether the fuel-vapor system can hold pressure or vacuum.

Can a gas cap cause P0442?

Yes. A loose cap, wrong cap, or damaged cap seal is one of the most common causes.

Can I drive with P0442?

Usually yes. The vehicle often drives normally, but you should fix the leak soon and pay attention to fuel smells or inspection failures.

Do I need a smoke test for P0442?

Not always, but it is often the fastest way to find a small leak after the gas cap and visible hoses check out.

What is the difference between P0442 and P0455?

P0442 points to a smaller EVAP leak, while P0455 usually indicates a larger leak that is easier to spot.

09 / Source and method

DATA BASIS
OBD-II REFERENCE + OBD2.HELP
METHOD
STATIC VALIDATION
SAFETY
INFORMATIONAL

This page combines OBD-II diagnostic reference data with OBD2.help generated diagnostic guidance for code meaning, likely causes, and repair direction.

Publishing uses deterministic schema and build validation, plus manual spot checks on representative pages before release.

Safety-critical diagnosis and repairs should be confirmed with a qualified mechanic, especially when the vehicle is misfiring, overheating, or losing power.